1. Field of the Invention
The present invention relates to a technique for inspecting a semiconductor device or a photo device.
2. Description of the Background Art
There is already known a semiconductor inspecting device which detects an electromagnetic wave emitted from a semiconductor device by irradiating it with pulsed laser light, thereby to inspect the semiconductor device in non-contact (e.g., Japanese Patent Application Laid-Open No. 2010-60317). In the semiconductor inspecting device described in Japanese Patent Application Laid-Open No. 2010-60317, a previously set inspection range is scanned with pulsed laser light in the semiconductor device by use of a galvanometer scanner. Then, the generated electromagnetic wave (terahertz wave) is detected, thereby to image its intensity distribution.
Further, the present applicant proposed a technique of irradiating a photo device with pulsed light and detecting an electromagnetic wave emitted from the photo device accordingly, thereby to inspect the photo device (Japanese Patent Application Laid-Open No. 2013-19861). In Japanese Patent Application Laid-Open No. 2013-19861. it is proposed that the photo device is moved in two-dimensional directions, thereby to scan the photo device with pulsed light.
As in the semiconductor inspecting device described in Japanese Patent Application Laid-Open No. 2010-60317, scanning by means of the galvano scanner enables relatively high-speed inspection of a certain range of an inspecting target. However, the semiconductor inspecting device described in Japanese Patent Application Laid-Open No. 2010-60317 is a so-called coaxial epi-illumination type inspecting device where the pulsed laser light, with which the semiconductor device is irradiated, is coaxial with the detected terahertz wave. In such a coaxial epi-illumination type inspecting device, it has been necessary to provide an optical plate with an ITO film so as to reflect the terahertz wave while transmitting the pulsed laser light. This might lead to a complicated configuration of the inspecting device, and improvement has thus been required.